The video, posted on the "Keep Jahi McMath on Life Support" Facebook page shows a person's hand rubbing ice on the Oakland girl's feet. A woman's voice can be heard pointing out movement of the left foot and right big toe.

"I don't understand how a brain-dead person can do this," the woman says.

McMath, 13, was declared brain dead after suffering complications from tonsil surgery Dec. 9 at Oakland Children's Hospital. Doctors sought to remove her from life support but the family intervened. She was removed from the facility Jan. 5, and her present location is not known.

Doctors told the Contra Costa Times the movement is hardly uncommon for brain dead patients.

Dr. Neal Slatkin, a neurologist and chief medical officer at San Jose's Hospice of the Valley, said more than half of brain dead patients move involuntarily as a result of muscle spasms or other physical responses -- perhaps in this case as a response to the cold ice.

That doesn't mean it's a conscious effort by McMath, he said.

"She's brain dead. She has no thought. She has no ability to control or interact with anything in her environment," Slatkin said. "She's completely dependent on machines and forever will be."

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